package experiment2;

import java.util.Scanner;

public class BigFigure {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long X = in.nextLong();
        long Y = in.nextLong();//定义并初始化两个大整数
        int length = in.nextInt();
        long answer = multiplyNum(X, Y, length);
        System.out.println(answer);
    }

    public static long multiplyNum(long X, long Y, int n) {
        if (X == 0 || Y == 0) return 0;//其中某一整数为零
        if (n == 1) return X * Y;//如果达到了可计算的标准(不一定为一位)
        int length = n / 2;//位数划分
        long A = X / (int) (Math.pow(10, length));
        long B = X % (int) (Math.pow(10, length));
        long C = Y / (int) (Math.pow(10, length));
        long D = Y % (int) (Math.pow(10, length));//拆分整数
        long AC = multiplyNum(A, C, length);
        long BD = multiplyNum(B, D, length);//继续拆分
        long E = multiplyNum(A + B, C + D, length);
        if (n % 2 == 0)
            return AC * (long) (Math.pow(10, n)) + BD + (E - AC - BD) * (long) (Math.pow(10, length));
        else
            return AC * (long) (Math.pow(10, n - 1)) + BD + (E - AC - BD) * (long) (Math.pow(10, length));
    }
}